When using a kitchen sink, such as during the washing of dishes, it is common to use a sink stopper to plug the drain, thus precluding water and debris from draining from the sink and flowing down into the drain. Such sink stoppers typically comprise a circular strainer basket that generally covers the opening of the drain, with a plurality of drainage apertures disposed in the strainer basket. The drainage apertures are shaped and dimensioned to permit the flow of water therethrough, but to preclude the passage of most debris. An annular rubber seal is disposed underneath the strainer basket of the sink stopper and is shaped to engage the mouth of the insert assembly of the drain, so as to provide a seal between the sink stopper and the insert assembly.
Sink stoppers also include a centrally disposed locating stem depending from the strainer basket. The stem is used to guide the sink stopper into a central guiding aperture in a perforated portion of the insert assembly of the drain.
The main function of a sink stopper is to cover the opening of the drain of a sink when the sink stopper is seated on the insert assembly, thus precluding water and debris from flowing down into the drain. The secondary function of a sink stopper is that of a strainer, wherein water is permitted to flow down into the drain, while most of the debris in the water, specifically the relatively large size debris such as pieces of food, is precluded from flowing down into the drain. Accordingly, sink stoppers typically have two distinct in-use positions at the mouth of the insert assembly of the drain, namely a seated flow precluding position and a raised straining position. In the seated flow precluding position, the sink stopper is disposed at the mouth of the insert assembly such that the annular rubber seal engages the mouth of the insert assembly so as to provide a seal between the sink stopper and the insert assembly. In the raised straining position, the sink stopper is disposed slightly above its seated flow precluding position, preferably only a slight distance above the insert assembly, such that only a small radial clearance exists between the periphery of the sink stopper and the surrounding wall of the insert assembly. The small radial clearance must be small enough to preclude the passage of debris contained within the water within the sink from passing between the sink stopper and the mouth of the insert assembly.
It is desirable that the sink stopper be manually movable downwardly from its raised straining position to its seated flow precluding position, by means of an easy and simple downwardly directed pushing effort, so that the sink stopper can be pushed to its seated flow precluding position quickly, if necessary, to stop water and small debris from flowing down the drain. It is also desirable that the sink stopper be manually moveable upwardly from its seated flow precluding position to its raised straining position by means of a relatively easy and simple effort, since the sink stopper must be raised against the downwardly directed force of the weight of the water in the sink.
Once the sink stopper has been situated in its raised straining position, the sink stopper must remain readily in its raised straining position of its own accord, without being held there by auxiliary means such as a person's fingers. Further, it should be possible to remove the sink stopper from the insert assembly so as to permit direct access to the insert assembly, to permit replacement of the sink stopper, and so on. Such lifting of the sink stopper from its raised straining position and subsequent removal from the insert assembly, should be somewhat difficult, but not overly difficult, so as to discourage the unnecessary removal of the sink stopper, thus minimizing possible misplacement of the sink stopper when not in use.